This study will be conducted in accordance with the Declaration of Helsinki and with the Colombian legislation as per the Resolution 8430/93 from the Ministry of Health. Prior to the admission of the patients in the study, the objectives and the methodology will be explained and the informed consent obtained. The study was approved by the Research Ethic Committee of the Cardiovascular Foundation of Colombia (Act# 105/January 28/2005). The right to confidentiality of the patients will be maintained in all the phases of the study.